1. Field of the Invention
This invention relates to explosives, and more particularly to acoustic crystal explosives.
2. Description of the Related Art
An explosive material is a material that either is chemically or otherwise energetically unstable or produces a sudden expansion of the material usually accompanied by the production of heat and large changes in pressure (and typically also a flash and/or loud noise) upon initiation; this is called the explosion or detonation.
A chemical explosive is a compound or mixture which, upon the application of heat or shock, decomposes or rearranges with extreme rapidity, yielding much gas and heat. A reaction must be capable of being initiated by the application of a shock wave or heat to a small portion of the mass of the explosive material. A detonation wave is essentially a shock wave supported by a trailing exothermic reaction. Detonation involves a wave traveling through a highly combustible or chemically unstable medium, such as an oxygen-methane mixture or a high explosive. The chemical reaction of the medium occurs following the shock wave, and the chemical energy of the reaction drives the wave forward.
Primary explosives are extremely sensitive to mechanical shock, friction, and heat, to which they will respond by burning rapidly or detonating. Examples include mercury fulminate, lead styphnate and lead azide. Primary explosives are easy to initiate but inherently less stable. Secondary explosives, also called base explosives, are relatively insensitive to shock, friction, and heat. They may burn when exposed to heat or flame in small, unconfined quantities, but detonation can occur. These are sometimes added in small amounts to blasting caps to boost their power. Dynamite, TNT, RDX, PETN, HMX, and others are secondary explosives. PETN is the benchmark compound; compounds more sensitive than PETN are classed as primary explosives. Secondary explosives are inherently more stable but hard to initiate. Often a primary explosive or “booster” is used to produce a shock wave with sufficient intensity to detonate the main charge of secondary explosives. Many customers would like to eliminate the use of primary explosives and use only secondary explosives.
Explosive force is released in a direction perpendicular to the surface of the explosive. If the surface is cut or shaped or “lensed”, the explosive forces can be focused to produce a greater local effect; this is known as a “shaped charge”. Multi-point initiation may be used to approximate a volumetric detonation. Achieving a desired shaped charge or a volumetric detonation is typically very expensive using known techniques.